Stabilized peracid solutions

Abstract

The current invention relates to the stabilisation of peroxyacid solutions. There is provided a tin based stabiliser composition obtained by the ageing of an alkaline solution of a tin compound and a phosphorus containing compound. The stabiliser is particularly suitable for the stabilisation of non-equilibrium solutions of peroxyacids.

We claim: 
     
       1. A process for the stabilisation of an aqueous solution of a peroxyacid prepared from a plurality of components by means of the addition of an effective amount of a tin based stabiliser to said solution or to one or more of said components of said solution, wherein said stabiliser is prepared as a coloured solution, which is aged for a time sufficient to obtain its fading before said addition to said peroxyacid solution or to one or more of said components of said solution and to obtain a clear solution having no suspended solids. 
     
     
       2. A process according to claim 1, wherein the peroxyacid comprises a peroxycarboxylic acid. 
     
     
       3. A process according to claim 1 wherein the stabiliser is prepared according to the following steps: a) preparing a solution containing a water soluble salt of a stannate with one or more water soluble phosphorus containing salts;   b) adjusting the pH of the solution to a pH in the range of 9 to 11.5, thereby forming a yellow solution; and   c) ageing the solution until the yellow coloration fades.   
     
     
       4. A process for the stabilisation of an aqueous solution of a peroxyacid prepared from a plurality of components by means of the addition of an effective amount of a tin based stabiliser to said solution or to one or more of said components of said solution, wherein the stabiliser is prepared according to the steps of: a) preparing a solution containing a water soluble salt of a stannate with one or more water solution phosphorus containing salts;   b) adjusting the pH of the solution to a pH in the range of 9 to 11.5; and   c) ageing the solution for a period determined by the formula Time=y(2.3.sup.(100-T)/10) in which time is given in hours, y is the range of from 0.1 to 2, and T is the temperature at which the solution is aged, in Celsius, whereby color of the solution fades and a clear solution having no suspended solids is obtained.   
     
     
       5. A process according to claim 3 or 4, wherein the phosphorus containing salt is selected from one or more of phosphate, condensed linear polyphosphate, or cyclic polyphosphate. 
     
     
       6. A process according to claim 5, wherein the phosphorus containing salt comprises a phosphate. 
     
     
       7. A process according to claim 3 or 4, wherein the pH of the solution is adjusted in the range of 10.9 to 11.1. 
     
     
       8. A process according to claim 3 or 4, wherein the solution ageing of step c) is carried out at an elevated temperature. 
     
     
       9. A process according to claim 4, wherein the amount of tin and phosphorus containing salts is at least 0.005% w/w of the composition. 
     
     
       10. A process according to claim 9, wherein the amount of tin and phosphorus containing salts combined is up to 1% w/w of the solution of the peroxyacid. 
     
     
       11. A process according to claim 1 or 4, wherein the peroxyacid comprises peracetic acid. 
     
     
       12. A process according to claim 1 or 4, wherein the peroxyacid is present at an equilibrium concentration. 
     
     
       13. A process according to claim 1 or 4, wherein the peroxyacid is present at greater than an equilibrium concentration and wherein the tin based stabiliser inhibits the reversion of the peroxyacid into hydrogen peroxide and the corresponding acid. 
     
     
       14. Stabilised aqueous peroxyacid composition prepared from a plurality of components, said composition comprising an effective amount of a tin based stabiliser said stabiliser being prepared as a coloured solution which is aged for a time sufficient to obtain its fading before introduction into the peroxyacid solution or to one or more of said components thereof and to obtain a clear solution having no suspended solids. 
     
     
       15. A composition according to claim 14, wherein the peroxyacid comprises a peroxycarboxylic acid. 
     
     
       16. A composition according to claim 14 wherein the stabiliser is prepared according to the following steps: a) preparing a solution containing a water soluble salt of a stannate with one or more water soluble phosphorus containing salts;   b) adjusting the pH of the solution to a pH in the range of 9 to 11.5, thereby forming a yellow solution; and   c) ageing the solution until the yellow coloration fades.   
     
     
       17. Stabilised aqueous peroxyacid composition, prepared from a plurality of components, said composition comprising an effective amount of a tin based stabiliser which has been prepared prior to its introduction into the composition or into one or more of said components thereof by steps of: a) preparing a solution containing a water soluble salt of a stannate with one or more water solution phosphorus containing salts;   b) adjusting the pH of the solution to a pH in the range of 9 to 11.5; and   c) ageing the solution for a period determined by the formula Time=y(2.3.sup.(100-T)/10) in which time is given in hours, y is the range of from 0.1 to 2, and T is the temperature at which the solution is aged, in Celsius, whereby color of the solution fades and a clear solution having no suspended solids is obtained.   
     
     
       18. A composition according to claim 16 or 17, wherein the phosphorus containing salt is selected from one or more of phosphate, condensed linear polyphosphate, or cyclic polyphosphate. 
     
     
       19. A composition according to claim 18, wherein the phosphorus containing salt comprises a phosphate. 
     
     
       20. A composition according to claim 16 or 17, wherein the pH of the solution is adjusted in the range of 10.9 to 11.1 in step b). 
     
     
       21. A composition according to claim 14 or 17 wherein the stabiliser is aged at an elevated temperature. 
     
     
       22. A composition according to claim 16 or 17, wherein the amount of tin and phosphorus is at least 0.005% w/w of the solution of the peroxyacid. 
     
     
       23. A composition according to claim 16 or 17, wherein the amount of tin and phosphorus is at least 1% w/w of the solution of the peroxyacid. 
     
     
       24. A composition according to claim 14 or 17, wherein the peroxyacid comprises peracetic acid. 
     
     
       25. A composition according to claim 14 or 17, wherein the peroxyacid is present at an equilibrium concentration. 
     
     
       26. A composition according to claim 14 or 17, wherein the peroxyacid is present at greater than an equilibrium concentration and wherein the tin based stabiliser inhibits the reversion of the peroxyacid into hydrogen peroxide and the corresponding acid.